Conventionally, an Oldham ring is widely used for a scroll compressor as one of rotation-preventing mechanisms for orbiting a driven member such that the driven member does not rotate when a rotation force of a driving member is transmitted to the driven member.
A conventional scroll compressor using the Oldham ring which is one of the rotation-preventing mechanisms will be described with reference to drawings (see patent document 1 for example). FIG. 10(a) is an exploded perspective view of a compressing mechanism of a conventional scroll compressor as viewed from a fixed scroll. FIG. 10(b) is an exploded perspective view of an orbiting scroll and an Oldham ring of the conventional scroll compressor as viewed from their back surfaces. FIG. 11 is a plan view of a bearing member and the Oldham ring of the scroll compressor shown in FIG. 10 as viewed from a back surface of the bearing member 106.
FIG. 11 shows, by dotted lines, an orbiting panel 108 of the orbiting scroll 109 and a keyway 115. An envelope circle in which an outer diameter of a seal member 121 disposed in the bearing member 106 is in contact with a back surface 117 of the orbiting panel 108 is shown by a phantom line.
In FIGS. 10(a) and 10(b), the compressing mechanism 101 includes a crankshaft 103, the bearing member 106, the orbiting scroll 109, the fixed scroll 111 and the Oldham ring 112.
The crankshaft 103 includes an eccentric shaft 102. The bearing member 106 includes a main bearing 105 which rotatably supports a main shaft 104 of the crankshaft 103. The orbiting scroll 109 includes a driving shaft 107 which is rotatably fitted into the eccentric shaft 102, the driving shaft 107 is provided on the orbiting panel 108, and an orbiting scroll blade 110 is provided on the orbiting panel 108 on a side opposite from the driving shaft 107. The fixed scroll 111 includes a fixed scroll blade (not shown) which meshes with the orbiting scroll blade 110 of the orbiting scroll 109 to form a plurality of compression spaces. An outer periphery 122 of the bearing member 106 and the fixed scroll 111 which is in contact with the outer periphery 122 are fixed to each other through a plurality of bolts.
A pair of scroll-side keys 113 are provided on one of surfaces of the Oldham ring 112, and a pair of bearing-side keys 114 are provided on the other surface of the Oldham ring 112.
A pair of scroll-side keyways 115 with which the scroll-side keys 113 slide are provided on the back surface 117 of the orbiting panel 108 of the orbiting scroll. 109 on its diameter line.
Bearing-side keyways 116 on which the bearing-side keys 114 slide are provided in a back surface 118 of the bearing member 106 on its diameter line.
A sliding direction of the scroll-side keys 113 the scroll-side keyways 115 and a sliding direction of the bearing-side keys 114 in the bearing-side keyways 116 intersect with each other at right angles.
A thrust support 119 which supports the orbiting panel 108 in a thrust direction is provided on the back surface 118 of the bearing member 106. An annular groove 120 is provided in the thrust support 119. The seal member 121 is provided on the annular groove 120. Different pressures are applied to an inner side and an outer side of the seal member 121, and when the compressor is operated, the orbiting scroll 109 is biased toward the fixed scroll 111 under an optimal force.
Rotation of the crankshaft 103 is transmitted to the driving shaft 107 of the orbiting scroll 109. The orbiting scroll 109 is moved in a first direction which is restricted by the scroll-side keys 113 and the scroll-side keyways 115, and in a second direction which is restricted by the bearing-side keys 114 and the bearing-side keyways 116, and rotation of the orbiting scroll 109 is inhibited. Since the first direction and the second direction intersect with each other at right angles, movement in the first direction and movement in the second direction are combined with each other, and the orbiting scroll 109 orbits with an orbiting radius e. As the orbiting scroll 109 orbits, the seal member 121 moves with the orbiting radius a with its surface which is in contact with the orbiting panel 108. A diameter of an envelope circle of the seal member 121 at its contact surface is a value of an outer diameter of the seal member 121 to which twice of the orbiting radius e is added.
According to the above-described configuration, if a rotation force from a motor (not shown) is transmitted from the crankshaft 103 to the orbiting scroll 109, the plurality of compression spaces formed between the orbiting scroll 109 and the fixed scroll 111 move from an outer peripheral side toward an inner peripheral side and with this movement, fluid is compressed. Therefore, fluid sucked from a suction port 123 of the compressing mechanism 101 is compressed and discharged from a discharge port 124.